A switchgear quotation is an engineering statement with a price attached. When the engineering is missing, the price is a placeholder, and placeholders have a habit of moving once the real drawing arrives.
These are the inputs that make the difference. None of them is exotic; all of them are usually available somewhere in the project file.
1. Single-line diagram
The most important document. It shows the incoming arrangement, the outgoing feeders, the ratings and the protection. A PDF is ideal; a clear photograph of a marked-up printout is workable; a verbal description is not.
2. Load list
Connected load per feeder, demand factor, and the spare capacity you want to keep. Two boards with the same total current can need different busbars depending on how the load is distributed.
3. Prospective short-circuit current
The fault level at the board decides the busbar rating, the breaking capacity of the devices and, in many cases, the assembly type. Where it is not calculated yet, say so, and the quotation can be issued with a stated assumption that is visible to both sides.
4. Voltage and frequency
230/400 V at 50 Hz is the common case in most export markets we work with, but 60 Hz and other distributions appear regularly. State the supply and the earthing arrangement (TN-S, TN-C-S, TT).
5. Enclosure and environment
IP rating, indoor or outdoor, ambient temperature, altitude, dust and humidity. A board in an air-conditioned electrical room and one in a corrugated kiosk in a coastal yard are different products.
6. Form of separation and access requirements
How far the operator must be separated from live parts, and whether feeders need to be workable while the busbar is live. This changes the internal structure, the price and the lead time.
7. Cable entry and termination
Bottom or top entry, cable or busway, gland plate dimensions and the direction the site will pull from. This is the single most common cause of site rework, and it costs nothing to confirm at enquiry stage.
8. Approved component brands
The vendor list your client has approved for breakers, contactors, relays, meters and terminals. Where no list exists, ask for a proposal with two options at different price points. It is easier to approve a device than to replace one.
9. Delivery and documentation requirements
Destination port, required on-site date, the standard the project is built to, and the documents the client expects: GA drawing, schematic, terminal list, test record, type test copy. Documentation requirements affect the schedule, so they belong in the enquiry.
The two that arrive late
Metering and communication. Whether metering is at the incoming only or per feeder, and whether readings go to a BMS or SCADA. It changes devices, wiring and sometimes the panel layout.
Spare capacity. Spare ways and spare space cost little at build stage. Adding them after the frame is fabricated is a rebuild.
A template that works
If you send nothing else, send these six lines and attach the drawing:
- Supply: 400 V, 50 Hz, TN-S, fault level 25 kA
- Board: main distribution, 1600 A busbar, 12 outgoing feeders + 2 spare
- Enclosure: IP54, indoor electrical room, ambient 40 °C
- Devices: Siemens or Schneider, per attached vendor list
- Cable entry: bottom, gland plate 600 × 200 mm
- Delivery: CIF Mombasa, needed on site by March
That is enough for a usable quotation, and enough for the supplier to come back with the three questions that actually matter.